Do alternator brushes have a break-in period? | Ford Explorer - Ford Ranger Forums - Serious Explorations

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Do alternator brushes have a break-in period?

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Just replaced the well worn factory brushes on the stock voltage regulator of the 95A alternator, due to symptoms of slightly flickering gauges/headlights.

However, after replacing, the alternator isn't charging the battery. Getting just 12.4 Volts at the battery, with the battery idiot light on and the voltage gauge closer to the left side than the right.

The new brushes are still square on the ends, compared to the well-worn original brushes that are of course shaped to fit the slip ring they contact.

Anyone know if a low/no charge condition is normal on these 3G alternators until a new brush assembly is broken in?

I checked fuses, the voltage regulator is good, no other electrical issues. Doesn't seem like a brush assembly can be bad, it's just the contacts soldered to the wires.
 


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Dang it.

I know the alt itself is good, it was doing just fine and a consistent 14+ volts prior to the brush replacement.

Guess I get to reinstall the old brush assembly and see if that makes it go back to normal.
 




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I will check, but I'm pretty sure they're making contact since they make an audible snap when pulling the retaining pin out after installation. My guess is the new brushes just aren't making enough contact with the slip ring due to the wear from the old brushes, but maybe the old ones won't work either and I've toasted something simply from alternator/brush removal and installation.
 




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Replaced the brush assembly with the original, same problem. So I guess it's not the new brushes, unless they caused something internal.

I'm getting 3.8 ohms between the slip rings, and infinite resistance between the shaft and windings, so I don't think it's the rotor, plus I'd be surprised if it just went bad from removing the regulator and replacing the brushes.

I've got 0.5 ohms from the alt terminal to the battery positive terminal with the negative terminal off, so it doesn't seem to be a short in the alt/battery connection either. Everything else works, 15A fuse from the alt to fuse box is good, all other wiring looks ok.

Not sure what's going on here unless the alt was going out and removal finally broke it.


I'm aware of the large case 3G and small/large case 6G compatibility. I haven't had any reliability issues with this unit so far. I'll probably just spring for a new Motorcraft 130A 3G as a replacement, but for now I'd just like to get the charging system back up ASAP so I can drive it until the replacement arrives.


EDIT: Also getting 12.8V at the rear alt terminal connection, and at both regulator screws, both when grounded at the battery and on the rear of the alt housing. Thought maybe the regulator went, doesn't seem to be the problem either.
 




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Took it all apart again, double checked the brushes, made sure they snapped against the slip rings, double checked all the wiring again for shorts or issues, have continuity everywhere, no broken connections, 12.8V at the battery, alternator terminal, regulator screws.

Still getting a battery light and low voltage on the gauge, and 12.4V at the batt terminals with the engine running. It's not charging, but I'm stumped as to what it could be from just changing the brushes if nothing else is wrong.

Any ideas?
 




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There could be a problem with the voltage regulator or a fuse could have blown. Check the fuse block under the hood with the large fuses. If they are fine, then remove the alternator, and have it bench tested.
 




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I'm guessing it is the regulator, either an internal diode or whatever else it has, since there's not much else to it and the rectifier going from fine to bad seems unlikely with a brush change.

I'll have it bench tested tomorrow, and either rebuild it, have it done since I can't pull the slip rings and small bearing myself, or just try for a regulator fix.
 




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Oh well.

Took it to the local alternator/starter shop to have it tested. A shop monkey whisked it off the counter, put it on the test bench, and of course it gave the same result as on the vehicle, not putting out proper voltage. So he takes it to what I assumed was a repair counter, hits it with a BFH, then brings it back to me and tells me it's completely broken and I have to buy a new one. The blow put a 2 inch crack in the main casing.

The shop owner wasn't really paying attention when all this happened, and just relies on what the guy tells him, but I'm not happy about bringing in a good alternator I just wanted checked out and probably rebuilt and then having the case cracked to force me to buy a new one. Guy offers me a shop rebuilt 95A 3G that's been fitted with aftermarket stuff and spray painted black (including the windings and internal components) for $67.50. I ask about a large case 130A 3G instead, he has one.

So now I have a World Power Systems (the same cheap ones that are all over ebay) 130A large case 3G with my stock 95A (which I kept) as a sacrifice, and $72.12, the cost of a rebuild.

Guess I still haven't learned my lesson about not having other people work on my stuff. They just don't care, except about making money, and with the least amount of work.

Sucks, this place used to be a good rebuilder.

Doesn't seem worth it to rebuild the stocker anymore, I'll essentially be replacing everything except the rear housing piece.

Guess I should have kept the 3 cheap regulators I returned just last week, would have given me something to try rather than have it tested and destroyed in the process.

Now I'm in the same boat as everyone else, trying to find a good 3G alternator.

At least the WPS one works ok, for now. Probably sell it later or keep as a spare.

:(
 




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The ones from alternatorparts.com (or National Quick Start Sales) seem to just be the same Motorcraft "Type" 3G's that are all over ebay for much less, or what I saw in the shop I got mine from. They had 160A, 200A, 240A, 3G/6G WPS alternators on the shelf. I don't see any point in paying $169.99 for what is probably the same WPS alternator I currently have. From what I gather, most "new" alternators are now of this WPS type, 100% made in China and shipped over by the boatload. They are decent, but with just a one year warranty and going by what I've seen, they don't appear to be designed to exceed that by much.

I wouldn't take one from AutoZone if it were free, except maybe to use as a paperweight. The threads on here are good enough proof for me that their alternators are junk that doesn't last. Having to make several trips to the store to keep trying alternators or replacing it every few hours/days/weeks until you get a good one isn't worth the cost. Obviously they are overpriced too, to absorb the cost of replacements.

I'm looking for an OE-Quality part like the brand new Motorcrafts were. Ford no longer sells brand new 3G alternators though. I should have bought a reman ACDelco when I saw it a year ago for cheap. They seem to have the best remanufacturing in the business, or at least they used to. Not sure if that's true anymore.

It would be nice if the Quick Start ones were better than what I think they are though. Cost isn't the issue, quality is. I want a heavy duty alternator like my stock 95A was, that will go for the next 200,000 miles (and beyond, if someone doesn't hit it with a hammer to kill it). I'm not interested in high amperage alts, or stuff like a $399-499 Mean Green, but I'd sure be willing to buy a new Motorcraft for some stupid price if I ever find one.

I'm staying away from "Motorcraft type" and "New" made in China electrical parts. The 130A 3G I have now is worse than the stock 95A I had with 225,000 miles on it and all the revolutions at idle along the way. It runs HOT (the 95A was just warm), and it kicks the voltage gauge needle down when anything electrical is used, including the headlights. With the 95A, the only time it ever kicked down was when hitting the power windows, and even then only if I held the switch too long when the window was done going up. Sure, it's charging at 14.6 at idle, but something tells me that 130 amps is a wishful rating, and this thing is probably putting out less than my stock 95A ever did.

In any case I'll be keeping a lookout for the best new/reman 130A I can get, and probably a starter now too just to keep as a backup. Another lesson learned the hard way. Buy an alternator and starter when you can get them cheap, and keep as a backup for when you have problems. Then you're not at the mercy of whatever you can get ASAP just to get back on the road.
 








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Yeah, I threw my 2 cents into the high output alternator thread not long ago.

I would just get a new NAPA one, but there are some reports those aren't anything special either. Not really interested in the 200A either for the price plus the wiring kit.

I'll probably bide my time waiting for a killer deal on the AC Delco stuff to come around again, or reman Motorcraft, if that ever happens.

As much as I want to just take the WPS alternator back for a refund (or just demand a refund and keep the alternator in exchange for breaking mine) and get something better on there ASAP, I doubt I'll get anything from the shop other than the "deal" of the alternator for the rebuild price I already received, so I may as well try it out. Plus it's got a one year warranty. I'll sure be returning it if I get the slightest hint it's screwing up the electrical system though.
 








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Probably was, but I had sent off the three voltage regulators I had last week so didn't have one to throw on and check.

Should have waited until I could get a Genuine Motorcraft VR to replace it with anyway, but that's in hindsight.

At this point I'm still fuming over having my OE Alt cracked and paying for a WPS Made in China one. Maybe I could throw a new VR on it even with the cracked case to check, but I doubt it'd be very safe, there could be a lot of other stuff damaged in there now.
 




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